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Genetic Testing and SCA

enetic testing of people who’ve suffered sudden unexplained death is an effective and cost-efficient way of identifying genetic mutations that may put surviving relatives at increased risk for potentially deadly heart rhythm disturbances, a new study suggests.

Genetic defects that can cause sudden cardiac death occur in 25 percent to 30 percent of victims of sudden unexplained death. The current recommended approach is for first-degree relatives of sudden unexplained death victims to undergo comprehensive cardiac testing.

In this study, U.S. researchers compared the results and costs of postmortem genetic/molecular autopsy testing in 146 sudden unexplained death cases and found that 40 of the victims (26.7 percent) had either a catecholaminergic polymorphic ventricular tachycardia mutation (18 people) or a long QT syndrome mutation (22 people). Both are known to cause sudden death.

The researchers then estimated the costs of testing the 584 relatives of the sudden unexplained death victims. The total cost of postmortem genetic testing, genetic confirmation testing of the 160 relatives of victims who tested positive for mutations, and cardiac tests for both relatives of mutation-positive and mutation-negative sudden unexplained death victims was $6.78 million.

In comparison, comprehensive cardiac testing for all 584 relatives of the sudden unexplained death victims, followed by directed genetic testing, would have been more than $7.7 million.

“With less than 150 sudden unexplained death cases, use of a cardiac channel molecular autopsy would be estimated to save almost $1 million indicating a much less expensive way of evaluating those left behind,” study co-author David Tester, a senior research technologist at Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minn., said in a news release.

“If you identify a mutation in a sudden unexplained death victim, you can do a simple genetic test in first-degree relatives to assess their risk and perform a disorder-directed clinical evaluation rather than a full clinical evaluation. If a relative is negative for the causative mutation, they may not need to undergo further clinical evaluation at all, and that saves money,” Tester explained.

The study was to be presented Sunday at the American Heart Association’s annual meeting in Orlando, Fla.